α-Synuclein knockdown attenuates MPP⁺ induced mitochondrial dysfunction of SH-SY5Y cells

Abstract

α-Synuclein is one of the main constituents of Lewy bodies and plays an important role in the pathology of Parkinson's disease. Mutation or overexpression of α-synuclein causes Parkinson's disease, and downregulation of α-synuclein resists MPP+-induced cell death, but the mechanism remains elusive. In this study, we attempted to explore the effect of α-synuclein knockdown on mitochondrial function in MPP+-treated SH-SY5Y cells. We reconstructed the short hairpin RNA expression vector, pGenesil-2, specially targeting α-synuclein mRNA, and it was stably transfected into SH-SY5Y cells. Cell viability, nuclear morphology, and mitochondrial membrane potential were then detected, and the expression of α-synuclein, cytochrome c, Bcl-2 and Bax were analyzed by Western blotting. The results showed that after exposure to 500 μM MPP+ for 24 h, about 41.0 ± 1.5% control cells showed low mitochondrial membrane potential. However, the percentage was 13.6 ± 1.2% in MPP+ treated α-synuclein knockdown cells. MPP+ induced cytochrome c release significantly, which was about 3.1-fold compared with that of control. However, in α-synuclein knockdown cells, the release of cytochrome c was blocked, which was about 1.4-fold compared with that of control. The Bcl-2/Bax ratio of SH-SY5Y cells reduced to 35.5 ± 3.8% after MPP+ treatment, and this ratio was 85.2 ± 3.0% in MPP+ treated α-synuclein knockdown cells. These data suggest that knockdown of α- synuclein might be an effective means in rescuing MPP+-induced mitochondrial dysfunction of SH-SY5Y cells. © 2009 Elsevier B.V. All rights reserved.